Improvement in electric lighting apparatus



T. A. EDISON. Electric Lighting Apparatus.

Patented Aug. 26,1879;

N. PETERS, FHOTQ-LH'HOGRLPNEH, WASHINGTON. n C.

UNITED STATES PATENT OEEIeE.

THOMAS A. EDISON, OF MENLO PARK, NEW JERSEY.

IMPROVEMENT IN ELECTRIC LIGHTING APPARATUS.

Specification forming part of Letters Patent NO. 21S,S66, dated August26, 1879 application filed December 9, 1878.

To all whom it may concern:

Be it known that I, THOMAS ALVA EDIsoN, of Menlo Park, in State of NewJersey, have invented an Improvement in Electric Lighting Apparatus, ofwhich the following is a specification.

In an application before filed by me, the light-giving body is combinedwith the circuitconnections and a thermal regulator that pre ventsinjury to the apparatus by short-circuiting the current or placing aresistance therein. I do not therefore herein claim any such device.

My present invention relates to the combination, with the light-givingbody, of a range of levers and contactsurfaces arranged in such a mannerthat the current is short-cit cuited or shunted to a greater or lessextent, according to the heat of the incandescent 1i ghtgiving body.

In the drawings, Figure 1 is an elevation of the bracket and a sectionof the light-giving apparatus. Fig. 2 is a sectional plan at the line a00. Figs. 3 and I are diagrams of the circuit-eonneetions; and Fig. 5 isa partial elevation endwise ot' the shunting-levers.

The bracket (4 is sustained by a socket and pin at b, so that it ,may beswung like a gastixture.

c is one of the electric conductors. The same is insulated and passesinto an opening in the bracket, and thence to the electric light, andthe return circuit is through the pipe (I to the wire d, or to thegas-pipe, if the bracket is upon a gas-pipe.

The conductor 0 passes to the insulated plate 0 within the case], and,for convenience, this cascf has a swinging door, f. in one side to giveaccess to the interior parts. Above the casef is a glass cylinder, it,or other suitable protection for the electric light, and 'i is a stripof platina-t'oil or other known or desired lightgiving material that canbe rendered incandescent and produce the necessary light withoutmelting. The conductor 0 passes to one end of this light, and the otherend of t is connected by the spring L with the metal part of thebracket, and thence to d.

The spring 7t serves to keep a slight tension on the foil i, and theyoke or frame 1 intervenes between the spring 75 and the foil.

There are levers a, or springs, that are connected at 2, and their freeends rest in and upon the yoke or frame 1, and their ends should betipped with platina.

The bar 0 is preferably of platina, and it is adjustable by means of thescrew in, that raises or lowers the same, so as to bring it nearer to orfarther from the ends of the levers or springs a. This adjustment ismade so that the ends of the springs or levers a will not be in contactwith the bar 0 while the light is in its normal condition; but when theheat of the foil 6 becomes excessive the expansion allows the ends ofthe springs or levers n to come into contact with the bar 0 and set up ashunt or short circuit from c 0, through a, to (7, and, according tothe. amount of expansion in '2', so one, two, or more of the bars orsprings n will be in contact with 0, because said bar ois farther fromthe levers a at one end than at the other. By this means injury to thelightgiving body is prevented, and a path established for the electriccurrent becomes less in resistance as the points of contact between a.

and 0 increase in number.

The lower end of the yoke I may come into contact with the spring orstud t at the extreme expansive movement, as seen in Fig. 4., to stillfurther lessen the resistance between 0 and d and divert the currentfrom the foil t'.

The ends of the levers a may be in a bath of mercury, as seen in Fig. 4,to insure electric contact. If the foili is accidentally broken orinjured the circuit through a is instantly closed, so that other lightsin the same circuit are not extinguished. This device is automatic, soas to avoid the extinguishment of other lights.

I claim as my invention 1. The combination, with the light-giving body,of two or more circuit levers or springs, 11, a yoke, l, a contact-bar,o, and the circuit connections, substantially as set forth, forlessening the resistance of the shunt as the temperature of thelightgivin g body increases, as specified.

2. The circuit-connection t, in combination with the levers or springsa, yoke I, light-giving body i, and circuit-counections, substantiallyas set forth.

Signed by me this 3d day of December, A.D. 1878.

\Vitnesses; THOIlIAS A. EDISON.

STOC L. GRIFFIN, GEo. E. OARMAN.

